Fibrous tobacco smoke filter elements



Aug. 9, 1960 J. C. WHITE FIBROUS TOBACCO SMOKE FILTER ELEMENTS Filed June 28, 1954 TOBACCO PARTICLES FILAMENTS James C. White INVENTOR.

By X

ATTORNEYS States Patent James C. White, Kingsport, Tenn., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed June 28, 1954, Ser. No. 439,920 r 2 Claims. ((31.131-208) The present invention relates to tobacco smoke filtering material and elements thereof suitable for use in cigarettes, pipes, cigarette holders, and cigar holders. More particularly, the invention is concerned with an improvement in filters of the general type disclosed in pending 'U.S. patent applications of Crawford and Stevens, Serial .No. 324,342, filed December 5, 1952, now Patent No.

2,900,988, and Serial No. 374,168, filed August 14, 1953, now Patent No. 2,794,480, to each of which reference is made.

In the aforementioned applications, newly discovered advantages of a certain type of fibrous tobacco smoke filter are discussed. The preferred type of filter is prepared from a specially conditioned tow of synthetically spun continuous filaments and comprises a structurally unitary rod-like mass of fibers and a wrapper encircling the mass, each fiber of the mass being substantially coextensive therewith, the fibers as a whole being in substantial alignment longitudinally of the mass but substantially each of the individual fibers having a plurality of short portions thereof crimped into diverging and converging relationship to the main fiber axis, a plurality of the fibers having surface solvation bonds to contiguous fibers at random points of contact. Very good results have been obtained in the use of such filters for the removal of nicotine and tars from tobacco smoke, especially in view of the fact that the filters supply other requirements gil ually as necessary to the success of a tobacco smoke ter.

These filters also have a marked processing advantage over other filters known in the art. However, since the fibers in these filters are substantially parallel to each other, some channelling of the smoke through the filter I may be possible, resulting in a decreased filtering action.

In other words, while interference with the smooth fiow of combustion products through the channels is provided by the random bonds between adjacent fibers, by incompleteness of fiber orientation, and by the short fiber per-- tions which are crimped into diverging and converging relationship to the main fiber axis, yet a certain amount of the smoke in the core of any minute column of smoke passing through the filter apparently maybe exposed in somewhat less than a theoretically maximum amount of contact with the fiber surfaces. Experimental investigations have shown that any attempt to reduce the siZe of smoke channels through the filters by an increase in filter density either through greater compaction or through the divergent and convergent fiber portions.

At the same time, the smoke filtering effectiveness of the filters described above has resulted in a belief among some smokers of unusual taste perceptivitythat a distinctive taste results, on account of the presence in the smoke .of some factor imparted by the filters. However, exten- 'use of finer fibers generally also results in an intolerable I sive research has indicated that, contrary to this belief, any perceptible taste change is due to removal of constituents of the gases, vapors, and smoke particles passing through the filters rather than to the addition of foreign constituents to the smoke stream. In any event, the fact remains that to some especially sensitive smokers a taste difference is, psychologically at least, objectionable.

I now have found that any perceptible taste difierence may be effectively obviated and that at the same time the efficiency of the filters described may be substantially increased without equivalent increase in pressure drop through the filter. This may be accomplished by depositing finely divided tobacco particles in the smoke channels provided by the spacing of adjacent fibers. I

This invention, therefore, has as one object the production of a more efiicient cigarette smoke filter consisting of a bundle of substantially longitudinally oriented textile fibers infused with finely divided tobacco particles. Another object is to provide means for increasing the efficiency of a cigarette filter prepared from a textile fiber. Another object of the invention is to obviate perceptible taste differences resulting from filtration of tobacco smoke. A still further object is provision of a filter which is capable of removing nicotine, tars, and other deleterious components of cigarette smoke without causing the smoke to be dry or distasteful. Another object is to increase the efficiency and improve the taste of tobacco smoke filters of the type disclosed in the above-identified Crawford and Stevens applications without creating a high pressure drop. Other objects will be obvious from the present specification and claims. I

Accordingly, the present invention consists, in general, in atobacco smoke filtering medium comprising a mass of substantially longitudinally aligned fibers, the spacing of substantially all groups of adjacent fibers providing minute passages for smoke therethrough, said mass carrying therein finely divided tobaccoparticles in an amount of 1 to 60%. by weight of the mass and said particles occupying positions in and partially blocking said passages whereby a substantial portion of the smoke is impinged either on the fibers or on the tobacco particles.

A more specific embodiment of the invention comprises a new tobacco smoke filtering material of synthetically spun continuous filaments and an element made therefrom, the element comprising a structurally unitary rod-like mass of fibers and a wrapper encircling the mass, each fiber of the mass being substantially coextensive therewith, the fibers as a whole being in substantial alignment longitudinally of the mass but substantially each of the individual fibers having a plurality of short portions thereof crimped into diverging and converging relationship to the main fiber axis, a plurality of the fibers having surface solvation bonds to contiguous fibers at random points of contact, the mass carrying substantially uniformly dispersed therein solid finely divided tobacco particles in the amount of 1 to 60% by weight of the mass.

Most advantageously, the invention comprises a filter of cellulose acetate fibers having surface solvation bonds achieved through the application of'a plasticizer spray, the filter carrying uniformly dispersed tobacco particles in the amount of about 5 to 30% by weight of the filter.

Any suitable means known to the art for spreading a powder onto a fibrous surfam or through a fibrous mass may be employed in preparing filters of the invention. Thus, for example, the tobaccopowder can be blown onto the fibers or it can be applied as a slurry in cold water or in a volatile organic vehicle or a plasticizer for the fibers. Still another method is to apply the tobacco powder to the fibers electrostatically, i.e. to inducev a charge on the fibers by friction or. other suitable means and then to run the fibers through a chamber" containing highly concentrated tobacco dust. Still another method for applying the tobacco is to wet the surface of the fibers with an adhesive or a plasticizer before exposing them to a powder spraying device. Preferably, the to- .bacco is continuously applied to an opened and handed moving tow formed as described in the Crawford and Stevens applications. That is to say, tow from a supply roll is opened to debundlize the filaments and provide a larger and more uniform tow cross section, and the opened tow is spread uniformly to a much larger width of e.g., 8 times its original width, thereby exposing substantially all of the filaments to material, i.e. plasticizer,

issuing from a dispenser adjacent which the tow passes.

tobacco smoke filter of the invention, and

Fig. 2 is a view of a cigarette, in part cut away, embodying a filtering element of the invention.

The invention is further illustrated in the following .examples:

Example 1 A crimped continuous filament tow of yarn type cellulose acetate of 5 denier per filament with a total denier of 100,000, and 9 crimps per inch was used to prepare filters in accordance wtih the preliminary conditioning procedure of Crawford and Stevens. The tow was pulled from a ball warp over stationary tensioning fingers and into a tensioning device functioning to provide tow opening as the first phase of filament separation. The device employed was of the type employing a pair of driven rolls to place under tension tow positioned in the ratch between the driven rolls and a pair of retarded rolls upstream of the driven rolls. The device was equipped with an improved reciprocating striker as disclosed and claimed in Smith pending US. patent application Serial No. 416,010, filed March 15, 1954. Upon being released from the nip of the positively driven tension rolls into a zone of relative relaxation, i.e. relatively little tension, the tow bloomed through inherent forces manifested upon the return of the tow to its original. condition.

The partially opened tow of cellulose acetate was slowly pulled 'over a compressed air banding device as disclosed in the aforementioned Crawford and Stevens patent applications and in pending US. patent application Serial 356,983, filed May 25, 1953, by Wallace T. Jackson. The banding device momentarily spread out the fibers to a width of six inches. While the tow was in this spread condition it was sprayed with a highly agitated slurry of one part of a commercial brand of powdered tobacco, i.e. snuff, in five parts dimethoxyethylphthalate plasticizer.

After this spreading and spraying treatment the tow was uniformly collected and fed to a garniture, i.e. a cigarette-making machine. The tow was fed through a shaping horn which served to condense the conditioned tow back into its original shape of a cord. The machine wrapped the tow with paper and cut it into rods similar in size to a standard size cigarette. The rods contained 1 part tobacco, 5 parts plasticizer and 25 parts cellulose acetate by weight. After the filter rods were given a short heat treatment to cause partial solvation of the acetate fibers by the plasticizer they were readily cut into 12 mm. filter tip lengths. These tips were attached by means of an adhesive tape to a standard brand of cigarettes available on the retail market in the US. The cigarettes were smoked on a smoking machine similar in design and operation to the smoking machine described by I. A. Bradford, W. R. Harlan and H. R.

Hammer in Industrial and Engineering Chemistry, vol. 28, pp. 836-9 (1936). The collected smoke was ana- .the rods were cut into 12 mm. lengths.

. 1 lyzed for nicotine and tars. The results of the smoking experiment were compared, with those obtained from smoking the same brand of cigarettes containing 12 mm. filter tips made from the same tow of cellulose acetate fibers plasticized with dimethoxyethylphthalate Without the addition of tobacco.

Type of Cigarette Filter Tip Mg. of Mg. of

(12 mm.) tars nicotine l Plasticized cellulose acetate tow 20 Plasticized cellulose acetate tow containing 1 3.2% tobacco powder 130 16 vent is unobstructed with any cigarette to be measured.

Example 2 A loose, i.e. partially opened tow of cellulose acetate containing approximately 10,000 fibers of 8 denier per filament was pulled through a bath containing a highly agitated slurry of 15% commercially available tobacco powder in cold water. When dried, the tow contained 14% of tobacco by weight uniformly dispersed throughout. The tobacco impregnated tow was processed into filter rods in a garniture as described in Example 1 and The filter tips so produced were attached to standard brand cigarettes and ten of these filter tipped cigarettes were smoked on the smoking machine. The collected smoke was analyzed for nicotine and tars. A control, consisting of the same brand of cigarettes tipped with filters made from the 8 denier per filament tow containing no tobacco was also smoked on the smoking machine and the collected smoke was analyzed in the same manner for nicotine and tars.

Mg. of tars Mg. of

nicotine Acetate tow filter Acetate tow filter containing 12% tobacco.

Moisture of the tobacco in each of the cigarettes:12.1%.

, cigarettes and extremely slight or no noticeable difference was reported by the panel.

Example 3 A tow of cellulose acetate yarn containing approximately 40,000 fibers of 3 denier per filament was spread out to a width of six inches and sprayed with a 10% solution of a water-base adhesive. While the tow was still spread out and wet with the adhesive it was sprayed with a commercially available finely divided dry tobacco powder and then rolled back into its original form. The impregnated tow was processed into filter rods and the rods were cut into 12 mm. lengths. The filter tips, containing 9% tobacco based on the weight of the acetate fibers, were attached to standard brand cigarettes and ten of these cigarettes were smoked on the smoking machine. The collected smoke was analyzed for nicotine and tars. A control consisting of the same brand of cigarettes tipped with a filter of the 3 denier per filament tow containing the adhesive but no tobacco was also smoked on the smoking machine and the collected smoke was analyzed into the same manner for nicotine and tars.

Moisture of the tobacco in each of the cigarettes=12.0%.

In carrying out the operation of this invention the type of tobacco employed is not a critical factor. Rather, the form of the tobacco is more important. The tobacco should be in a powdered form so that it can be readily slurried in a liquid or passed through a spraying nozzle. Any source of tobacco which passes this requirement can, therefore, be employed. Larger particles of tobacco such as granules, fiber, slivers, etc. can be employed so long as the particles are not so large as to cause sufficient fiber displacement which might increase channeling in the filter. However, the more finely divided materials, e.g. 100 to 200 mesh appear to be easier of'application and more effective as to filtering efiiciency.

I claim:

1. A filter for a cigarette comprised essentially of a filter element made up of a bundle of longitudinally oriented filaments, the filaments making up the bundle being characterized in that said filaments:

(a) are comprised of cellulose acetate,

(b) are continuous, crimped filaments,

(c) carry a content of plasticizer,

(d) carry tobacco particles of 100-200 mesh dispersed on the surface of the filaments, and the filaments of the bundle are coalesced to other filaments at random points of contact and to the tobacco particles by means of bonds obtained to a substantial extent by the aforesaid plasticizer content,

2. The method of preparing a filter element as set forth in claim 1 which comprises opening up and spreading out the continuous crimped cellulose acetate filaments, spraying said opened-up filaments with a liquid containing plasticizer and tobacco powder of -200 mesh, shaping the sprayed filaments into the form of a filter and wrapping the formed filter with a retaining wrapper.

References Cited in the file of this patent UNITED STATES PATENTS 1,310,404 Irving July 15, 1919 2,181,614 Streifling Nov. 28, 1939 2,190,107 Pohle Feb. 13, 1940 2,411,660 Manning Nov. 26, 1946 2,459,804 'Francis Jan. 25, 1949 2,476,582 Browne et a1. July 19, 1949 2,483,406 'Francis Oct. 4, 1949 2,579,984 Trowbridge Dec. 25, 1951 2,594,680 Rehfeld Apr. 29, 1952 2,688,380 MacHenry Sept. 7, 1954 2,707,308 Taylor et al May 3, 1955 2,739,598 Eirich Mar. 27, 1956 2,739,913 Lieser Mar. 27, 1956 2,774,680 -Hackney et a1. Dec. 6, 1956 2,798,850 Voightman et a1. July 9, 1957 2,815,761 Shearer Dec. 10, 1957 FOREIGN PATENTS 121,414 Australia Mar. 30, 1944 264,287 Switzerland Jan. 3, 1950 538,529 Great Britain Aug. 7, 1941 665,278 Great Britain Ian. 23, 1952 685,822 Great Britain Jan.'14, 1953 813,324 France May 31, 1937 

1. A FILTER FOR A CIGARETTE COMPRISED ESSENTIALLY OF A FILTER ELEMENT MADE UP OF A BUNDLE OF LONGITUDINALLY ORIENTED FILAMENTS, THE FILAMENTS MAKING UP THE BUNDLE BEING CHARACTERIZED IN THAT SAID FILAMENTS: (A) ARE COMPRISED OF CELLULOSE ACETATE, (B) ARE CONTINUOUS, CRIMPED FILAMENTS, (C) CARRY A CONTENT OF PLASTICIZER, (D) CARRY TOBACCO PARTICLES OF 100-200 MESH DISPERSED ON THE SURFACE OF THE FILAMENTS, AND THE FILAMENTS OF THE THE BUNDLE ARE COALESCED TO OTHER FILAMENTS AT RANDOM POINTS OF CONTACT AND TO THE TOBACCO PARTICLES BY MEANS OF BONDS OBTAINED TO A SUBSTANTIAL EXTENT BY THE AFORESAID PLASTICIZER CONTENT. 